1. Field of the Invention
This invention relates generally to devices for location positioning and more particularly relates to a method for identifying an environmental source emitting a base frequency and waveform signal.
The present invention also relates to a system for performing the method and a computer program for performing the method.
2. Description of the Related Art
In various modern applications, it is essential for a device to know its location. Usually it suffices to know the room in which the device is located. This allows the application to be tailored to the location of a user of the device. This way, a so-called context-aware device is capable of adjusting its operations to fit the context in which the device is introduced. Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and application themselves. Almost any information available at the time of an interaction can be seen as context information. Some examples are:
spatial information—e.g., location, orientation, speed, and acceleration;
environmental information—e.g., temperature, air pressure, light, and noise level;
resources that are nearby—e.g., accessible devices, and hosts;
availability of resources—e.g., battery, display, network, and bandwidth; and
physiological measurements—e.g., blood pressure, heart rate, respiration rate, and muscle activity.
A system is context-aware if it can extract, interpret and use context information and adapt is functionality to the current context of use. The challenge for such systems lies in the complexity of capturing, representing and processing contextual data. To capture context information, generally, some additional sensors and/or programs are required. To transfer the context information to applications and for different applications to be able to use the same context information, a common representation format for such information should exist. In addition, to being able to obtain the context-information, applications must include some “intelligence” to process the information and to deduce the meaning. This is probably the most challenging issue, since context is often indirect or deducible by combining different pieces of context information. E.g., if three persons meet in a certain office room at a certain time, it can mean that it is the weekly strategy meeting. Another situation would be when a context-aware application, such as a context-aware mobile phone, is placed in front of the user's personal computer at work, the application could then be given the information that the user do not wish to be disturbed with private phone calls.
There are features that are characteristic for context-aware applications. Firstly, information and services can be presented to the user according to the current context. This includes the selection of proximate information and services, and contextual commands. Secondly, automatic execution of a service may be performed when being in a certain context. This includes context-triggered actions and contextual adaptation. An example of the previous would be that when a user enters a specific room, his/her mails would be shown on a nearby terminal. An example of the latter would be the change on volume on a phone according to a current noise level.
A very evident type of application is the ability to find nearby resources. This can include input and output devices: printers, displays, speakers, facsimiles, video cameras, thermostats, etc. In pure service lookup, actually even no location information needs to be used. In situations where, e.g., distance calculations have to be done, location information of a device is required.
The usage of context information is still quite limited since it is very challenging and complex to capture, represent, and process contextual data. The most used types of context information are location, identity and time information. The context-aware application development is mainly concentrated around user interfaces, virtual and augmented reality, mobile, handheld and wearable computing. There are very few commercial products using context information yet, because of the challenges in this field.
There are several ways to obtain required location information. A variety of tracking systems exists, some of them based on the Global Positioning System (GPS) with which the location of a device can be determined. Systems for a positioning network, such as the GPS, are known for the purpose to locate virtually any place on the planet. However, such tracking systems are quite expensive which makes them unacceptable for low-cost consumer electronics. Other solutions involve the installation of positioning devices, such as GSM, DECT or Bluetooth beacons, etc. Furthermore it is known to adapt existing devices to act as sources of position information.
A lighting source can be modified to operate at a specific known frequency which can be detected by a device and transacted to a location. U.S. Pat. No. 5,657,145 discloses a method of transmitting coded data signals by modulating the output from light sources, e.g., electric lamps. The visible light wave is used as a carrier wave whereon the signals are transmitted. A wide range of digital information can be transmitted, such as audio and video content, etc. Of course, this modulation can also be used to identify the light source.
However, the light sources have to be modified to transmit the requested information and thereby be identified. It will, though, be advantageous not to modify ambient light sources for several reasons.